Clamp bar for fabrics

ABSTRACT

A clamp bar for fabrics consisting of a straight bar having a straight top shoulder to which the edge of a large sheet of fabric may be drawn, and a series of clamps carried at intervals along the bar for clamping the fabric thereto. The clamps are operated by compressed air, and each is actuated to clamp the fabric by pressing it manually toward its operative position, whereupon the compressed air takes over to hold it in position. All of the clamps may be released simultaneously by pressing a pushbutton valve.

I mted States Patent [191 [111 3,861,663 Strickland Jan. 21, 1975 CLAMPBAR FOR FABRICS 3,095,190 6/1963 Freund 269/32 x [76] Invento Robert V.Stric and, 9021 Wedd 3,306,603 2/1967 21ers 269/91 Overland Park, Kans.66212 Primary Examiner Roy Lake [22] Filed: Nov. 9, 1973 AssistantExaminer-Mark S. Biclts [211 App]. NOI: 414,264 Attorney, Agent, orFirm-John A. Hamilton 52 U S Cl 26 26 8 91 269 I [57] ABSTRACT 1 9/ 3 4A clamp bar for fabrics consisting of a straight bar [51] Int CI B25)/06 having a straight top shoulder to which the edge of a [58] Fie'ld 91large sheet of fabric may be drawn, and a series of 269/ 32 34 clampscarried at intervals along the bar for clamping the fabric thereto. Theclamps are operated by com- [56] References Cited pressed air, and eachis actuated to clamp the fabric by pressing it manually toward itsoperative position, UNITED STATES PATENTS whereupon the compressed airtakes over to hold it in 1,501,044 7/1924 Dwoirln 38/108 iti All of theda ps may be released simulta- 2,269,328 1/1942 Williamson 269/26 Xneously by pressing a pushbutton va]ve 2,323,770 7/1943 Hazelton 269/221X 2,327,920 8/1943 Moohl..... 269/32 X 8 Claims, 7 Drawing Figures O RJ5 4 135 2 16 as 1 m c (Q) j x I z i 5 2 2 a ,0 J /Z 4 Z d CLAMP BAR FORFABRICS This invention relates to new and useful improvements in fabrichandling equipment, and has particular reference to a device forclamping an edge of a large sheet of fabric to a straight bar, so thatthe fabric may be drawn across a supporting surface, such as a largetable, so that operations such as cutting, hemming, or the like may beperformed on its opposite edge with the assurance that the edge on whichsaid operations are being performed is truly parallel to the clampededge. Clamp bars of this general type are used, for example, to insureparallelism of a cut or hemmed edge of a drapery panel in relation to apreviously cut or hemmed opposite edge. The difficulties of handlingvery large sheets of fabric under these circumstances are well known. Indraperies, the edge to be cut or hemmed may be 32 feet long or evenlonger. But while the present device has been conceived primarily foruse in drapery forming operations, it will be readily apparent that ithas general applicability in many fields.

A principal object of the present invention is the provision of a fabricclamp bar consisting of a bar along which an edge of a large sheet offabric may be arranged in an accurately straight line, and a series ofclamps carried in spaced relation along the length of said bar and eachoperable to clamp the fabric to the bar.

Another object is the provision of a clamp bar of the characterdescribed in which the clamps are compressed air-actuated, but may beindividually actuated simply by pressing each clamp toward its operativeposition against a spring, the compressed air taking over automaticallyat a predetermined point to complete the setting of the clamp. In thismanner, the operator may use one hand to align that portion of thefabric to be engaged by a particular clamp, and the other hand toactuate the clamp.

A further object is the provision of a fabric clamp bar of the characterdescribed wherein the clamps, though individually actuated, may bereleased simultaneously simply by pressing a pushbutton.

Other objects are simplicity and economy of construction, efficiency anddependability of operation, and adaptability for use in a wide varietyof applications.

With these objects in view, as well as other objects which will appearin the course of the specification, reference will be had to theaccompanying drawing, wherein:

FIG. 1 is a front elevational view of a portion of a fabric clamp barembodying the present invention,

FIG. 2 is a top plan view of the fabric clamp bar as shown in FIG. 1,

FIG. 3 is an enlarged sectional view taken on line III- III of FIG. 1,showing one of the clamps in its released position,

FIG. 4 is a fragmentary view similar to FIG. 3, with the clamp at anintermediate stage in the actuation thereof,

FIG. 5 is a view similar to FIG. 3, showing the clamp fully engaged,

FIG. 6 is a fragmentary sectional view taken on line VI-Vl of FIG. 4,and

FIG. 7 is an enlarged sectional view taken on line VII- VII of FIG. 2.

Like reference numerals apply to similar parts throughout the severalviews, and the numeral 2 applies to a table or other supporting surfaceover which it may be desired to draw a large sheet of fabric 4 by meansof a clamp bar device indicated generally by the numeral 6, andconsisting of an elongated base bar 8 lying on and movable over thetable surface, and means for clamping an edge of the fabric to said bar.The base bar may be mounted on and movable over the table surface,usually by power means insuring parallelism of the bar to an edge of thetable, but such bar mounting and moving means are not pertinent to thepresent invention, and are not shown. The base bar is provided with alongitudinally extending, forwardly facing shoulder 10 against which anedge of fabric 4 may be drawn to insure straight, linear positioning ofsaid fabric edge, the top surface of the bar providing a horizontalledge 12 forwardly of shoulder 10, with its extreme forward edge portionbeing bevelled as indicated at 14.

The fabric 4 is adapted to be clamped to ledge 12 by means of a seriesof foot bars 16 arranged parallel to base bar 8 thereabove, said footbars being disposed directly above ledge 12 and spaced in a series alongbase bar 8. Each foot bar may be about 9 inches long, with 2 inchesbetween adjacent ends thereof, although this spacing is of courseoptional. Clamp bars 30 to 40 feet long are not uncommon. Each foot baris rigid, though it may be covered with a smooth plastic material, notshown, to prevent snagging or tearing of the fabric, and

is movable downwardly from an elevated position well above ledge 12, asshown in FIG. 3, to a position clamping fabric 4 against ledge 12, asshown in FIG. 5.

Each foot bar 16 is supported by a vertically yieldable spring yoke 18from the forward end of a rigid horizontal arm 20, said arm extendingrearwardly from said yoke and entering a vertically elongated slot 22formed in a tubular post 24, said post being fixed at its lower end inbar 8 behind shoulder 10 thereof. Said post acts as a pneumaticcylinder, and is sealed at its upper end. Within each post, the rearwardend of the associated arm 20 is affixed, as by set screw 26, in thelower end of a pneumatic piston 28 carried operably in said post. Saidpiston'is biased upwardly in the post by a compression spring 30. Theupper portion of the piston is bored out as indicated at 32 to behollow, and is provided with a side air passage 34 at the bottom of thebore thereof. Air passage 34 cooperates with a vertically elongated ventslot 36 formed in the wall of post 24, in a manner to be described. Eachpost 24 is also provided with a side air inlet port 38 spaced below theupper end thereof, the ports 38 of all of the posts being interconnectedby branch pipes 40 with a common air supply pipe 42 which extendshorizontally behind posts 24 the full length of the base bar. At one endof the base bar, pipe 42 is connected through a pressure release valve44 to a pipe 46, which in turn is connected by a hose 48 to any suitablesource of compressed air, not shown. Hose 48 is flexible to permit readymovement of the base bar over the table.

As best shown in FIG. 7, release valve 44 includes a valve body 50having therein a slidable plunger 52 having a passageway 54. The plungeris normally biased by spring 56 to the position shown, whereinpassageway 54 interconnects pipes 46 and 42, but may be moved againstspring 56 by manual pushbutton 58 to a position in which pipe 46 issealed off, and passageway 54 interconnects pipe 42 to a vent hole 60formed in the valve body, whereby pipe 42 is vented to the atmosphere.

In operation, it will be seen that when each clamp is released, it hasthe position shown in FIG. 3, the foot bar 16 thereof being spaced wellabove ledge 12 of the base bar, being elevated and retained in thisposition by spring 30, with arm 20 engaged in the upper end of post slot22. In this position, the cylinder inlet port 38 is sealed off by thepiston, so that the piston is not lowered, and piston air passage 34 isin communication with post vent slot 36, so that any air which mightleak past the piston is vented to the atmosphere. The operator thenarranges fabric 4 beneath the foot bar, bringing the fabric edge intocontact with shoulder of the base bar, and then actuates the clamp tolower the foot bar 16 against the fabric as in FIG. 5.

To actuate the clamp, the operator first manually lowers the foot baragainst the pressure of spring 30, for example by pressing downwardly onarm 20, to the position shown in FIG. 4. This movement may be veryeasily accomplished, since piston passage 34 is still in communicationwith slot 36 so that no vacuum can form above the piston, and sincespring 30 need be no stronger than is required to elevate and supportthe weight of the associated piston 28, arm 20, spring yoke 18 and footbar 16. At the FIG. 4 position, piston passage 34 passes beyond postslot 36 and is sealed off, and the piston uncovers port 38, so thatcompressed air enters the post above the piston and forces said pistondownwardly until foot bar 16 clamps fabric 4 firmly against ledge 12 asin FIG. 5. The downward motion of arm 20 is limited by engagementthereof in the lower end of slot 22. In the FIG. 5 position, it will beseen that spring yoke 18 has yielded to some degree. This yieldabilityof the yoke permits the foot bar to better adapt to the fabric surface,for example if the fabric is folded, and also prevents possible injuryto the operator in the event he has a finger under the foot bar as thepiston is lowered past the FIG. 4 position. It will thus be seen thateach clamp may be actuated separately as needed, and this is consideredto be advantageous singe large sheets of pliable fabric are notoriouslyhard to handle, and the present arrangement permits it to be positionedone section at a time proceeding from one end of a long edge, with eachsection being clamped in place as it is positioned.

The clamps are all released simultaneously by momentary pressure onpushbutton 58 of release valve 44. This vents all of the air cylinderposts to the atmosphere, so that the pistons are elevated by springs 30.During the initial portion of the rise of each piston, until it israised to the FIG. 4 position, air is vented through ports 38. At theFIG. 4 position, the piston seals port 38, but piston passage 34 theninterconnects with slot 36, so that the piston can complete its upwardmovement with no possibility that impeding air pressure can formthereabove.

While I have shown and described a specific embodiment of my invention,it will be readily apparent that many minor changes of structure andoperation could be made without departing from the spirit of theinventron.

What I claim as new and desire to protect by Letters Patent is:

l. A clamp bar for engaging an edge portion of a sheet of fabriccomprising:

a. an elongated base bar over which the edge portion of said fabricsheet may be laid,

b. a series of clamp devices mounted on said base bar in spaced relationtherealong and each including a foot bar movable between an elevatedposition well above said base bar and a lowered position wherein itclamps said fabric against said base bar, and

0. operating means operable to move said foot bars selectively betweensaid elevated and lowered positions, said operating means for each footbar including power means operable when actuated to lower said foot barto its lowered position, and means operable by manual lowering of saidfoot bar a predetermined proportion of its travel to said loweredposition to actuate said power means.

2. A clamp bar as recited in claim I wherein said power means for eachof said clamp devices comprises:

a. spring means normally biasing the associated foot bar to its elevatedposition,

b. air pressure-actuated means operable when supplied with air underpressure to lower said foot bar to its lowered position,

c. air pressure control means operable by manual lowering of said footbar through a portion of its movement, against said spring means, tosupply air under pressure to said air pressure-actuated means, and

d. manually operable means for exhausting air from said air-pressureactuated means.

3. A clamp bar as recited in claim 2 wherein said manually operablemeans for exhausting air from said air pressure-actuated means isoperable to exhaust air simultaneously from the air-pressure actuatedmeans of all of said clamp devices.

4. A clamp bar as recited in claim 1 wherein each of said clamp devicesand its operating means comprises:

a. a vertical pneumatic cylinder fixed at its lower end in said base barand sealed at its upper end.

b. a piston vertically movable in said cylinder 0. an arm fixed to saidpiston and projecting outwardly through a vertically elongated slot ofsaid cylinder, the associated foot bar being carried at the outer end ofsaid arm, and

d. spring means biasing said piston upwardly in said cylinder to raisesaid foot bar to its elevated position, said cylinder being providedwith an air inlet port connected to a source of air under pressure, saidinlet port being sealed by said piston when in said elevated positionbut opened to supply air to said cylinder above said piston when saidpiston is moved manually downwardly against said spring means apredetermined portion of its travel to its lowered position.

5. A clamp bar as recited in claim 4 wherein said foot bar is connectedto the outer end of said arm by means of a vertically yieldable spring.

6. A clamp bar as recited in claim 4 wherein said piston is providedwith an air passage opening into said cylinder above said piston andthrough a side of the piston below the upper end thereof, said cylinderhaving a side vent opening below said inlet port which cooperates withthe side opening of said piston air passage to seal said piston airpassage at all positions of the upper end of said piston at or belowsaid inlet port, and to vent said piston passage to the atmosphere atall positions of the upper end of said piston above said inlet port.

common conduit, and an atmospheric vent, spring means biasing said valveto a first position in which the inlet and outlet thereof areinterconnected and said atmospheric vent is sealed, and manuallyoperable means for moving said valve to a second position in which saidoutlet and vent are interconnected, and said inlet is sealed.

1. A clamp bar for engaging an edge portion of a sheet of fabriccomprising: a. an elongated base bar over which the edge portion of saidfabric sheet may be laid, b. a series of clamp devices mounted on saidbase bar in spaced relation therealong and each including a foot barmovable between an elevated position well above said base bar and alowered position wherein it clamps said fabric against said base bar,and c. operating means operable to move said foot bars selectivelybetween said elevated and lowered positions, said operating means foreach foot bar including power means operable when actuated to lower saidfoot bar to its lowered position, and means operable by manual loweringof said foot bar a predetermined proportion of its travel to saidlowered position to actuate said power means.
 2. A clamp bar as recitedin claim 1 wherein said power means for each of said clamp devicescomprises: a. spring means normally biasing the associated foot bar toits elevated position, b. air pressure-actuated means operable whensupplied with air under pressure to lower said foot bar to its loweredposition, c. air pressure control means operable by manual lowering ofsaid foot bar through a portion of its movement, against said springmeans, to supply air under pressure to said air pressure-actuated means,and d. manually operable means for exhausting air from said air-pressureactuated means.
 3. A clamp bar as recited in claim 2 wherein saidmanually operable means for exhausting air from said airpressure-actuated means is operable to exhaust air simultaneously fromthe air-pressure actuated means of all of said clamp devices.
 4. A clampbar as recited in claim 1 wherein each of said clamp devices and itsoperating means comprises: a. a vertical pneumatic cylinder fixed at itslower end in said base bar and sealed at its upper end. b. a pistonvertically movable in said cylinder c. an arm fixed to said piston andprojecting outwardly through a vertically elongated slot of saidcylinder, the associated foot bar being carried at the outer end of saidarm, and d. spring means biasing said piston upwardly in said cylinderto raise said foot bar to its elevated position, said cylinder beingprovided with an air inlet port connected to a source of air underpressure, said inlet port being sealed by said piston when in saidelevated position but opened to supply air to said cylinder above saidpiston when said piston is moved manually downwardly against said springmeans a predetermined portion of its travel to its lowered position. 5.A clamp bar as recited in claim 4 wherein said foot bar is connected tothe outer end of said arm by means of a vertically yieldable spring. 6.A clamp bar as recited in claim 4 wherein said piston is provided withan air passage opening into said cylinder above said piston and througha side of the piston below the upper end thereof, said cylinder having aside vent opening below said inlet port which cooperates with the sideopening of said piston air passage to seal said piston air passage atall positions of the upper end of said piston at or below said inletport, and to vent said piston passage to the atmosphere at all positionsof the upper end of said piston above said inlet port.
 7. A clamp bar asrecited in claim 4 wherein compressed air from a suitable source issupplied to the inlet ports of all of said cylinders through a commonconduit, and with the addition of release means manually operable torelease air from said common conduit.
 8. A clamp bar as recited in claim7 wherein said release means comprises a valve having an inlet connectedto said air source, an outlet connected to said common conduit, and anatmospheric vent, spring means biasing said valve to a first position inwhich the inlet and outlet thereof are interconnected and saidatmospheric vent is sealed, and manually operable means for moving saidvalve to a second position in which said outlet and vent areinterconnected, and said inlet is sealed.